Ophthalmic solutions are sterile solutions, free from foreign particles, for instillation into the eye. In some uses, they do not have medications in them and are only lubricating and tear-replacing solutions or eye washes. In other uses, they have active ingredients in them and can be used to treat such conditions as dry eye, allergies, eye infections such as pink eye or conjunctivitis, or eye conditions such as glaucoma. They can also be used by opticians as mydriatic compositions to dilate the pupils of patients during eye examinations.
Anionic polymers such as hyaluronic acid and carboxyl vinyl polymers have been found useful in ophthalmic solutions for the treatment of eye conditions such as dry eye.
To avoid introducing infective agents into the eye, it is critical that ophthalmic solutions remain sterile in their storage containers between uses. Polyquaternium compounds are polycationic polymers that are used as surfactants in the personal care industry. Some have antimicrobial properties, and can find use as a preservative in contact lens solutions.
An issue with polyquaternium compounds is their tendency to react with anionic materials. In eye care solutions containing anionic polymers, attempts to increase the concentration of polyquaternium in the compositions results in the formation of a precipitate. The precipitate is believed to be the complexation product of anionic polymer and the polyquaternium.
There is, therefore, a need for compositions containing polyquaternium compounds with anionic polymers having reduced precipitate formation or complexation.
The present inventors have found that an amount of an organic acid effective for binding with the polyquaternium in at least a 1:1 molar ratio to inhibit, reduce or prevent the precipitation and/or complexation of the polyquaternium compound and the anionic polymer.
It is therefore an aspect of the present invention to provide compositions comprising a polyquaternium compound and an anionic polymer wherein the precipitation or complexation of the polyquaternium compound and an anionic polymer is reduced or prevented.
A further aspect of the present invention relates to composition comprising a polyquaternium compound, an anionic polymer and an effective amount of an organic acid such that precipitation and/or complexation of the polyquaternium compound and an anionic polymer is inhibited, reduced or prevented.